Why does a four leaf clover brings good luck?

It's just that finding a four-leaf clover is extremely difficult since it is a "mutant" clover. If you were able to find such a "mutant" clover, you'd be a very lucky person. I've hunted for one for a long time as a child, but never found one. So, you actually need the luck to find the four-leaf clover, even though people say you get the luck from the four-leaf clover. People just associate the four-leaf clover with luck and that's why they say that it "brings" good luck.

Also, perhaps there is more to this question. In many cultures, it is widely believed that four-leaf clover brings luck, so it might be coming from an old belief or a specific culture. We should know what other distinct cultures say about it.